A LED is a p-n junction diode that can emit light of various wavelengths, and has the characteristics of low power consumption, low heat generation, long operational life, small volume, good impact resistance, fast response, and excellent stability, so that the LED has been popularly used in electric appliance field as a light source.
In optoelectric applications, a LED also has been used as an important active component of optical fiber communications, due to its reliability and high beam-coupling ratio with the optical fiber. Generally, to obtain high light-coupling efficiency with optical fibers, a point source LED is selected as the light source of communications, because of its lower view angel. However, a conventional LED having a bonding area located on the center of the light emitting area not only restricts the light emitting that can affect the emitting shape, but also reduces the light emitting efficiency.
To resolve this problem, a lens is provided to concentrate the light emitted from the point source LED into a light beam. However, the addition of lens requiring additional assembly processes and materials is not competitive in the market.
U.S. Pat. No. 6,063,643 provides a method of concentrating the local current into a LED to produce the concentrated emitting light. In the disclosed art, a light-emitting diode is etched to form an emitting area. Then the epitaxy structure and the electrode surrounding the light emitting area are selectively oxidized. By the treatment, the conventional problems of light emitting restriction can be avoided, so that, the emitted light can be focused into a light beam without any additional lenses. However, only the materials suitable for oxidizing, such as AlGaAs or AlAs can be used as the epitaxy structure. And the treatment of selective oxidization conducted on the epitaxy structure can increase the complexity and cost of the LED manufacturing processes.
Japanese Unexamined Patent Publication (Kokai) No. Heisei 2-174272 discloses another LED of high brightness. In the disclosed art, by etching the epitaxy structure of the LED, a light emitting area is provided. Consequently, a circle electrode is provided by a series of doping and etching processes. Through the treatment, the lightness of the LED can be increased and the light can be concentrated into a single beam. However the doping process requires high operation temperatures that could cause the degradation of the LED.
It is desirable; therefore, to provide a point source LED with high lightness, concentrative emitting light, and with simple manufacturing processes.